nvme/{tree,fabrics}: do not crash when accessing disconnected controllers

When a controller is disconnected it will just clear the volatile attributes,
but remain part of the tree structure. So when traversing the tree one could
access a disconnected controller, but then c->name is NULL.
So fixup all places calling nvme_ctrl_get_name() to ensure that they don't
crash on an empty name.

Signed-off-by: Hannes Reinecke <[email protected]>

Author: hreinecke

src/nvme/fabrics.c

@@ -1149,6 +1149,13 @@ static struct nvmf_discovery_log *nvme_discovery_log(
 		.uuidx = NVME_UUID_NONE,
 	};
 
+	if (!name) {
+		nvme_msg(r, LOG_ERR,
+			 "controller not connected\n");
+		errno = ENOTCONN;
+		return NULL;
+	}
+
 	log = __nvme_alloc(sizeof(*log));
 	if (!log) {
 		nvme_msg(r, LOG_ERR,

src/nvme/tree.c

@@ -245,6 +245,9 @@ static void nvme_filter_ctrl(nvme_root_t r, nvme_ctrl_t c,
 	if (f(NULL, c, NULL, f_args))
 		return;
 
+	if (!nvme_ctrl_get_name(c))
+		return;
+
 	nvme_msg(r, LOG_DEBUG, "filter out controller %s\n",
 		 nvme_ctrl_get_name(c));
 	nvme_free_ctrl(c);
@@ -1815,6 +1818,8 @@ nvme_ctrl_t __nvme_lookup_ctrl(nvme_subsystem_t s, const char *transport,
 
 	c = p ? nvme_subsystem_next_ctrl(s, p) : nvme_subsystem_first_ctrl(s);
 	for (; c != NULL; c = nvme_subsystem_next_ctrl(s, c)) {
+		if (!nvme_ctrl_get_name(c))
+			continue;
 		if (ctrl_match(c, &candidate)) {
 			matching_c = c;
 			break;